Evaluation of a new, rapid latex test for the detection of heterophil antibody.

OBJECTIVE

To compare the performance of the MONO-LEX system to that of the MONO-TEST in detecting infectious mononucleosis (IM) heterophil antibodies.

SETTING

Baptist Regional Laboratories, Memphis, Tennessee.

PRACTICE DESCRIPTION: Not applicable. PRODUCT COMPARISON: The MONO-LEX system, manufactured by Trinity Laboratories, Raleigh, North Carolina, distributed by Gull Laboratories, Salt Lake City, Utah, and the MONO-TEST kit, manufactured by Wampole Laboratories, Cranbury, New Jersey, are agglutination assays that show visible agglutination when reagents are mixed with serum or plasma containing IM heterophil antibodies.

MAIN OUTCOME MEASUREMENTS: Accuracy in detecting heterophil antibodies in the study specimens, ease of interpreting test results, and cost-effectiveness.

RESULTS

Of the 139 specimens tested, 132 produced the same results using both products and seven produced discrepant results. The possibility that the MONO-TEST produced a "prozone effect" was eliminated. Titration of sera that tested positive for heterophil antibody by both methods revealed titers as high as 1:152 by the MONO-LEX compared with 1:128 by the MONO-TEST. A total of 31 specimens that tested positive for IgM antibodies to Epstein-Barr virus nuclear antigen by enzyme immunoassay were assayed using the two methods; MONO-LEX detected heterophil antibodies in eight sera while the MONO-TEST detected antibody in only four samples.

CONCLUSION

The MONO-LEX surpassed the MONO-TEST in sensitivity, cost-effectiveness, and ease of interpretation.